Curable (meth)acrylate compositions

ABSTRACT

A curable composition includes a multifunctional (meth)acrylate; a substituted or unsubstituted arylether (meth)acrylate monomer; and a polymerization initiator. The compositions exhibit high refractive indices and, upon polymerization, the compositions provide films having excellent thermomechanical properties.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation-in-part of application Ser.No. 10/249,998 filed May 21, 2003.

BACKGROUND OF INVENTION

[0002] Disclosed herein are curable (meth)acrylate compositions and,more specifically ultraviolet (UV) radiation curable (meth)acrylatecompositions. The compositions are suitable for optical articles andparticularly for light management films.

[0003] In backlight computer displays or other display systems, opticalfilms are commonly used to direct light. For example, in backlightdisplays, light management films use prismatic structures (oftenreferred to as microstructure) to direct light along a viewing axis(i.e., an axis substantially normal to the display). Directing the lightenhances the brightness of the display viewed by a user and allows thesystem to consume less power in creating a desired level of on-axisillumination. Films for turning or directing light can also be used in awide range of other optical designs, such as for projection displays,traffic signals, and illuminated signs.

[0004] Compositions used to form light management films to direct lightdesirably have the ability to replicate the microstructure needed toprovide the light directing capability upon cure. It is furthermoredesirable for the glass transition temperature (Tg) of the curedcomposition to be high enough for shape retention during storage anduse. It is also desirable for light management films made from the curedcomposition to exhibit high brightness. Finally, the composition used tomake light management film advantageously provides a cured compositionhaving a high refractive index (RI). While a variety of materials arepresently available for use in light management films, there remains acontinuing need for still further improvement in the materials used tomake them, particularly materials that upon curing possess the combinedattributes desired to satisfy the increasingly exacting requirements forlight management film applications.

SUMMARY OF INVENTION

[0005] The above-described needs are alleviated by a curable compositioncomprising a multifunctional (meth)acrylate; a substituted orunsubstituted arylether (meth)acrylate monomer, especially anarylthioether (meth)acrylate; and a polymerization initiator.

[0006] The above-described needs are also alleviated by a curablecomposition comprising a multifunctional (meth)acrylate; a substitutedor unsubstituted arylether (meth)acrylate monomer; a brominated aromatic(meth)acrylate monomer; and a polymerization initiator.

[0007] In one embodiment, a curable composition comprises amultifunctional (meth)acrylate represented by the formula:

[0008] wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2;and R² is represented by the formula:

[0009] wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y isdivalent C₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; a substituted orunsubstituted arylether (meth)acrylate monomer according to the formula:

[0010] wherein R³ is hydrogen or methyl; X² is 0 or S; R⁴ is substitutedor unsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar is substituted orunsubstituted C₆-C₁₂ aryl, including phenyl; wherein the substitution onthe R⁴ and Ar independently include fluorine, chlorine, bromine, iodine,C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ ketone, C₁-C₆ester, N,N-(C₁-C₃) alkyl substituted amide, or a combination comprisingat least one of the forgoing substituents; and a polymerizationinitiator.

[0011] In another embodiment, a curable composition consists essentiallyof a multifunctional (meth)acrylate represented by the formula:

[0012] wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2;and R² is represented by the formula:

[0013] wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y isdivalent C₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; a substituted orunsubstituted arylether (meth)acrylate monomer according to the formula:

[0014] wherein R³ is hydrogen or methyl; X² is O or S; R⁴ is substitutedor unsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar is substituted orunsubstituted C₆-C₁₂ aryl, including phenyl; wherein the substitution onthe R⁴ and Ar independently include fluorine, chlorine, bromine, iodine,C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ ketone, C₁-C₆ester, N,N-(C₁-C₃) alkyl substituted amide, or a combination comprisingat least one of the forgoing substituents; and a polymerizationinitiator.

[0015] A curable composition, comprises a multifunctional (meth)acrylaterepresented by the formula:

[0016] wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2;and R² is represented by the formula:

[0017] wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y isdivalent C₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; a substituted orunsubstituted arylether (meth)acrylate monomer represented by theformula:

[0018] wherein R³ is hydrogen or methyl; X² is O or S; X³ is O or S; R⁴is substituted or unsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar issubstituted or unsubstituted C₆-C₁₂ aryl, including phenyl; wherein thesubstitution on the R⁴ and Ar independently include fluorine, chlorine,bromine, iodine, C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ketone, C₁-C₆ ester, N,N-(C₁-C₃) alkyl substituted amide, or acombination comprising at least one of the forgoing substituents; abrominated aromatic (meth)acrylate monomer represented by the formula:

[0019] wherein R⁵ is hydrogen or methyl; X⁴ is O or S; X⁵ is O or S; mis 1, 2, or 3; p is 0 or 1; and q is 4 or 5; and a polymerizationinitiator.

[0020] Other embodiments, including a method of preparing a curablecomposition, a cured composition comprising the reaction product of thecurable composition, and articles comprising the cured composition, aredescribed below.

DETAILED DESCRIPTION

[0021] It has been unexpectedly discovered that the addition of asubstituted or unsubstituted arylthioether (meth)acrylate monomer to amultifunctional (meth)acrylate provides a curable composition havingexcellent RI as well as providing improved brightness when cured into amicrostructured film as compared to an analogous composition based on asubstituted or unsubstituted arylether (meth)acrylate monomer.

[0022] It has also been unexpectedly discovered that the addition of abrominated aromatic (meth)acrylate monomer to a multifunctional(meth)acrylate and a substituted or unsubstituted arylether(meth)acrylate monomer in the presence of a polymerization initiatorprovides a composition having improved RI. Furthermore, upon curing thecured composition exhibits improved Tg. Finally, a cured,microstructured film made from the curable composition exhibits improvedbrightness compared to cured, microstructured film made from curablecompositions lacking the brominated aromatic (meth)acrylate monomer.

[0023] As used herein, “(meth)acrylate” is inclusive of both acrylateand methacrylate functionality, in addition to thioester(meth)acrylatefunctionality (for example, CH₂═CH(R)(C═O)S—, wherein R is hydrogen ormethyl).

[0024] The terms “a” and “an” herein do not denote a limitation ofquantity, but rather denote the presence of at least one of thereferenced item. All ranges disclosed herein are inclusive andcombinable.

[0025] In one aspect, the curable composition is a solventless, highrefractive index, radiation curable composition that provides a curedmaterial having an excellent balance of properties. The compositions areideally suited for light management film applications. In one aspect,light management films prepared from the curable compositions exhibitgood brightness.

[0026] The curable compositions comprise a multifunctional(meth)acrylate, i.e., a molecule containing at least two (meth)acrylatefunctional groups. In a preferred embodiment, the multifunctional(meth)acrylate is represented by the formula (I)

[0027] wherein R¹ is hydrogen or methyl; X¹ is O or S; R² is substitutedor unsubstituted C₁-C₃₀₀ alkyl, aryl, alkaryl, arylalkyl, or heteroaryl;and n is 2, 3, or 4. The substitution on R² includes, but is not limitedto, fluorine, chlorine, bromine, iodine, C₁-C₆ alkyl, C₁-C₃perhalogenated alkyl, hydroxy, C₁-C₆ ketone, C₁-C₆ ester, N,N-(C₁-C₃)alkyl substituted amide, or a combination comprising at least one of theforgoing substituents. Preferred R² groups include such groups asalkylene and hydroxy alkylene disubstituted bisphenol-A or bisphenol-Fethers, especially the brominated forms of bisphenol-A and -F. SuitableR² groups include those according to the formula (II)

[0028] wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y isdivalent C₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is about 1 to about 3.

[0029] The multifunctional (meth)acrylates may include compoundsproduced by the reaction of acrylic or methacrylic acid with adi-epoxide, such as bisphenol-A diglycidyl ether; bisphenol-F diglycidylether; tetrabromo bisphenol-A diglycidyl ether; tetrabromo bisphenol-Fdiglycidyl ether;1,3-bis-{4-[1-methyl-1-(4-oxiranylmethoxy-phenyl)-ethyl]-phenoxy}-propan-2-ol;1,3-bis-{2,6-dibromo-4-[1-(3,5-dibromo-4-oxiranylmethoxy-phenyl)-1-methyl-ethyl]-phenoxy}-propan-2-ol;and the like; and a combination comprising at least one of the foregoingdi-epoxides. Examples of such compounds include2,2-bis(4-(2-(meth)acryloxyethoxy)phenyl)propane;2,2-bis((4-(meth)acryloxy)phenyl)propane; acrylic acid 3-(4-{1-[4-(3-acryloyloxy-2-hydroxy-propoxy)-3,5,-dibromo-phenyl]-1-methyl-ethyl}-2,6-dibromo-phenoxy)-2-hydroxy-propylester; acrylic acid 3-[4-(1-{4-[3 -(4-{1 -[4-(3-acryloyloxy-2-hydroxy-propoxy)-3,5-dibromo-phenyl]-1-methyl-ethyl}-2,6-dibromo-phenoxy)-2-hydroxy-propoxy]-3,5-dibromo-phenyl}-1-methyl-ethyl)-2,6-dibromo-phenoxy]-2-hydroxy-propylester; and the like, and a combination comprising at least one of theforegoing multifunctional (meth)acrylates. A suitable multifunctional(meth)acrylate based on the reaction product of tetrabrominatedbisphenol-A di-epoxide is RDX 51027 available from UCB Chemicals. Othercommercially available multifunctional (meth)acrylates include EB600,EB3600, EB3605, EB3700, EB3701, EB3702, EB3703, and EB3720, allavailable from UCB Chemicals, or CN104 and CN120 available fromSartomer.

[0030] In one embodiment, the multifunctional (meth)acrylate includesthose compounds according to the formula (III)

[0031] wherein R¹ is hydrogen or methyl; X¹ is O or S; Q is —C(CH₃)₂—,—CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y is divalent C₁-C₆ alkyl or hydroxysubstituted divalent C₁-C₆ alkyl; b is 1; t is 2; and d is 1; or whereinR¹ is hydrogen or methyl; X¹ is O or S; Q is —C(CH₃)₂—, —CH₂—, —C(O)—,—S(O)—, or —S(O)₂—; Y is divalent C₁-C₆ alkyl or hydroxy substituteddivalent C₁-C₆ alkyl; b is 1; t is 2; and d is 2; or a combinationthereof. Combinations which may make up the multifunctional(meth)acrylate component of the composition include two or morecompounds according to the formula (III).

[0032] The multifunctional (meth)acrylate is present in the curablecomposition in an amount of about 25 to about 75 weight percent based onthe total composition. Within this range, an amount of greater than orequal to about 35 weight percent may be used, with greater than or equalto about 45 weight percent preferred, and greater than or equal to about50 weight percent more preferred. Also within this range, an amount ofless than or equal to about 70 weight percent may be used, with lessthan or equal to about 65 weight percent preferred, and less than orequal to about 60 weight percent more preferred.

[0033] The curable composition further comprises a substituted orunsubstituted arylether (meth)acrylate monomer. A preferred substitutedor unsubstituted arylether (meth)acrylate monomer is represented by theformula (IV)

[0034] wherein R³ is hydrogen or methyl; X² is O or S; X³ is O or S; R⁴is substituted or unsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar issubstituted or unsubstituted C₆-C₁₂ aryl, including phenyl; wherein thesubstitution on the R⁴ and Ar independently include fluorine, chlorine,bromine, iodine, C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ketone, C₁-C₆ ester, N,N-(C₁-C₃) alkyl substituted amide, or acombination comprising at least one of the forgoing substituents. The Argroup, when substituted, may be mono-, di-, tri-, tetra- orpenta-substituted. As used herein, “arylether” is inclusive of botharylethers and arylthioethers, also known as arylsulfides, unlessotherwise indicated. Particularly preferred substituted or unsubstitutedarylether (meth)acrylate monomers include 2-phenoxyethyl (meth)acrylateand 2-phenylthioethyl (meth)acrylate.

[0035] The substituted or unsubstituted arylether (meth)acrylate monomeris present in the curable composition in an amount of about 15 to about70 weight percent based on the total composition. Within this range, itmay be preferred to use an amount of greater than or equal to about 20weight percent, more preferably greater than or equal to about 30 weightpercent. Also within this range, it may be preferred to use an amount ofless than or equal to about 60 weight percent, more preferably less thanor equal to about 50 weight percent, yet more preferably less than orequal to about 40 weight percent.

[0036] In one aspect, the composition may comprise two or moresubstituted or unsubstituted arylether (meth)acrylate monomers ofdifferent chemical compounds. In one embodiment, a first substituted orunsubstituted arylether (meth)acrylate monomer comprises the formula(IV) above wherein X³ is S and a second substituted or unsubstitutedarylether (meth)acrylate monomer comprising the formula (IV) wherein X³is O.

[0037] The brominated aromatic (meth)acrylate monomer may be present inthe curable composition to impart increased refractive index of thecurable composition or increased thermomechanical properties (i.e.,increased Tg) of the composition upon curing. Useful brominated aromatic(meth)acrylate monomers may be represented by the formula (V)

[0038] wherein R⁵ is hydrogen or methyl; X⁴ is O or S; X⁵ is O or S; mis 0, 1, 2, or 3; p is 0 or 1; and q is 1, 2, 3, 4, or 5. When m is 0, pis 0. Highly preferred brominated aromatic (meth)acrylate monomersinclude 2,4,6-tribromobenzyl (meth)acrylate, tetrabromobenzyl(meth)acrylate, tribromophenyl (meth)acrylate, pentabromophenyl(meth)acrylate, and pentabromobenzyl (meth)acrylate.

[0039] The brominated aromatic (meth)acrylate monomer may be present inthe curable composition in an amount of about 1 to about 20 weightpercent based on the total composition. Within this range, an amount ofgreater than or equal to about 3 weight percent may be used, with anamount of greater than or equal to about 4 preferred, and an amount ofgreater than or equal to about 5 weight percent more preferred. Alsowithin this range, it may be preferred to use an amount of less than orequal to about 15 weight percent, more preferably less than or equal toabout 10 weight percent, yet more preferably less than or equal to about8 weight percent.

[0040] The composition further comprises a polymerization initiator topromote polymerization of the (meth)acrylate components. Suitablepolymerization initiators include photoinitiators that promotepolymerization of the components upon exposure to ultraviolet radiation.Particularly suitable photoinitiators include phosphine oxidephotoinitiators. Examples of such photoinitiators include the IRGACURE®and DAROCUR™ series of phosphine oxide photoinitiators available fromCiba Specialty Chemicals; the LUCIRIN® series from BASF Corp.; and theESACURE® series of photoinitiators. Other useful photoinitiators includeketone-based photoinitiators, such as hydroxy- and alkoxyalkyl phenylketones, and thioalkylphenyl morpholinoalkyl ketones. Also suitable arebenzoin ether photoinitiators.

[0041] The polymerization initiator may include peroxy-based initiatorsthat may promote polymerization under thermal activation. Examples ofuseful peroxy initiators include, for example, benzoyl peroxide, dicumylperoxide, methyl ethyl ketone peroxide, lauryl peroxide, cyclohexanoneperoxide, t-butyl hydroperoxide, t-butyl benzene hydroperoxide, t-butylperoctoate, 2,5-dimethylhexane-2,5-dihydroperoxide,2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide,t-butylcumyl peroxide,alpha,alpha′-bis(t-butylperoxy-m-isopropyl)benzene,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumylperoxide,di(t-butylperoxy isophthalate, t-butylperoxybenzoate,2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide,trimethylsilylphenyltriphenylsilyl peroxide, and the like, andcombinations comprising at least one of the foregoing polymerizationinitiators.

[0042] In a preferred embodiment, the polymerization initiator comprisesa phosphine oxide photoinitiator.

[0043] The polymerization initiator may be used in an amount of about0.01 to about 10 weight percent based on the total weight of thecomposition. Within this range, it may be preferred to use apolymerization initiator amount of greater than or equal to about 0.1weight percent, more preferably greater than or equal to about 0.5weight percent. Also within this range, it may be preferred to use apolymerization initiator amount of less than or equal to about 5 weightpercent, more preferably less than or equal to about 3 weight percent.

[0044] The composition may, optionally, further comprise an additiveselected from flame retardants, antioxidants, thermal stabilizers,ultraviolet stabilizers, dyes, colorants, anti-static agents,surfactant, and the like, and a combination comprising at least one ofthe foregoing additives, so long as they do not deleteriously affect thepolymerization of the composition.

[0045] In another embodiment, a curable composition consists of amultifunctional (meth)acrylate according to the formula

[0046] wherein R¹ is H or methyl; X¹ is O or S; R² is substituted orunsubstituted C₁-C₃₀₀ alkyl, aryl, alkaryl, arylalkyl; or heteroaryl;and n is 2, 3, or 4; a substituted or unsubstituted arylether(meth)acrylate monomer according to the formula

[0047] wherein R³ is hydrogen or methyl; X² is O or S; X³ is S; R⁴ issubstituted or unsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar issubstituted or unsubstituted C₆-C₁₂ aryl including phenyl; wherein thesubstitution on the R⁴ and Ar is, independently, fluorine, chlorine,bromine, iodine, C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ketone, C₁-C₆ ester, N,N-(C₁-C₃) alkyl substituted amide, or acombination comprising at least one of the forgoing substituents; and apolymerization initiator.

[0048] In one aspect, the curable composition has a RI greater than orequal to about 1.54, with greater than or equal to about 1.56 preferred,greater than or equal to about 1.58 more preferred, and greater than orequal to about 1.59 most preferred.

[0049] In an additional aspect, the cured composition may have a RIgreater than or equal to about 1.54, with greater than or equal to about1.56 preferred, greater than or equal to about 1.58 more preferred, andgreater than or equal to about 1.59 most preferred.

[0050] In yet another aspect, the cured composition has a Tg of greaterthan or equal to about 40° C., with greater than or equal to about 60°C. preferred, greater than or equal to about 80° C. more preferred, andgreater than or equal to about 90° C. most preferred.

[0051] In one embodiment, where the cured composition is the reactionproduct of a multifunctional (meth)acrylate represented by the formula:

[0052] wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2;and R² is represented by the formula:

[0053] wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y isdivalent C₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; and a substituted orunsubstituted arylether (meth)acrylate monomer according to the formula:

[0054] wherein R³ is hydrogen or methyl; X² is O or S; R⁴ is substitutedor unsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar is substituted orunsubstituted C₆-C₁₂ aryl, including phenyl; wherein the substitution onthe R⁴ and Ar independently include fluorine, chlorine, bromine, iodine,C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ ketone, C₁-C₆ester, N,N-(C₁-C₃) alkyl substituted amide, or a combination comprisingat least one of the forgoing substituents; the cured composition has aTg of greater than or equal to about 40° C., with greater than or equalto about 45° C. preferred, and greater than or equal to about 50° C.more preferred.

[0055] In another aspect, light management films made from the curedcomposition containing a brominated aromatic (meth)acrylate monomerexhibits a brightness of greater than or equal to about 1400 candela permeter squared (cd/m²), with greater than or equal to about 1450 cd/m²preferred, and greater than or equal to about 1490 cd/m² more preferred.

[0056] The compositions provided herein comprising a substituted orunsubstituted arylthioether (meth)acrylate monomer, a multifunctional(meth)acrylate, and a polymerization initiator provide materials havingexcellent refractive indices without the need for the addition of knownhigh refractive index additives. Such compositions, when cured intomicrostructured films, thus provide films exhibiting excellentbrightness.

[0057] The curable composition may be prepared by simply blending thecomponents thereof, with efficient mixing to produce a homogeneousmixture. When forming articles from the curable composition, it is oftenpreferred to remove air bubbles by application of vacuum or the like,with gentle heating if the mixture is viscous. The composition can thenbe charged to a mold that may bear a microstructure to be replicated andpolymerized by exposure to ultraviolet radiation or heat to produce acured article.

[0058] An alternative method includes applying the radiation curable,uncured, composition to a surface of a base film substrate, passing thebase film substrate having the uncured composition coating through acompression nip defined by a nip roll and a casting drum having anegative pattern master of the microstructures. The compression nipapplies a sufficient pressure to the uncured composition and the basefilm substrate to control the thickness of the composition coating andto press the composition into full dual contact with both the base filmsubstrate and the casting drum to exclude any air between thecomposition and the drum. The radiation curable composition is cured bydirecting radiation energy through the base film substrate from thesurface opposite the surface having the composition coating while thecomposition is in full contact with the drum to cause themicrostructured pattern to be replicated in the cured composition layer.This process is particularly suited for continuous preparation of acured composition in combination with a substrate.

[0059] The curable compositions are preferably cured by UV radiation.The wavelength of the UV radiation may be from about 1800 angstroms toabout 4000 angstroms. Suitable wavelengths of UV radiation include, forexample, WVA, UVB, WVC, UVV, and the like; the wavelengths of theforegoing are well known in the art. The lamp systems used to generatesuch radiation include ultraviolet lamps and discharge lamps, as forexample, xenon, metallic halide, metallic arc, low or high pressuremercury vapor discharge lamp, etc. Curing is meant both polymerizationand cross-linking to form a non-tacky material.

[0060] When heat curing is used, the temperature selected may be about80° to about 130° C. Within this range, a temperature of greater than orequal to about 90° C. may be preferred. Also within this range, atemperature of greater than or equal to about 100° C. may be preferred.The heating period may be of about 30 seconds to about 24 hours. Withinthis range, it may be preferred to use a heating time of greater than orequal to about 1 minute, more preferably greater than or equal to about2 minutes. Also within this range, it may be preferred to use a heatingtime of less than or equal to about 10 hours, more preferably less thanor equal to about 5 hours, yet more preferably less than or equal toabout 3 hours. Such curing may be staged to produce a partially curedand often tack-free composition, which then is fully cured by heatingfor longer periods or temperatures within the aforementioned ranges.

[0061] In one embodiment, the composition may be both heat cured and UVcured.

[0062] In one embodiment, the composition is subjected to a continuousprocess to prepare a cured film material in combination with asubstrate. To achieve the rapid production of cured material using acontinuous process, the composition preferably cures in a short amountof time. It has been found that compositions containing substituted orunsubstituted bis(4-(meth)acryloylthiophenyl)sulfides exhibit lower curespeeds and/or lower degree of cure than corresponding compositions thatare free of such compounds. Accordingly, it is preferred that thecurable compositions of this embodiment do not comprise substituted orunsubstituted bis(4-(meth)acryloylthiophenyl)sulfides.

[0063] Current manufacturing processes for the low cost production ofcured films require rapid and efficient curing of materials. Thecompositions comprising a substituted or unsubstituted arylthioether(meth)acrylate monomer, a multifunctional (meth)acrylate, especiallythose corresponding to formulas (I) and (II), and a polymerizationinitiator have been found to efficiently cure under typical conditionsemployed for the rapid, continuous production of cured, coated filmsemploying UV irradiation. Such compositions exhibit excellent relativedegree of cure under a variety of processing conditions.

[0064] The relative degree of cure of the compositions after exposure toa WVA dose of about 0.289 joules/cm² is greater than about 70 percent,preferably greater than about 80 percent, and yet more preferablygreater than about 85 percent. One method of determining the relativedegree of cure is provided herein below.

[0065] In one embodiment, a curable composition comprises about 35 toabout 65 weight percent of a multifunctional (meth)acrylate; about 30 toabout 45 weight percent of a substituted or unsubstituted arylether(meth)acrylate monomer; about 1 to about 10 weight percent of abrominated aromatic (meth)acrylate monomer; and about 0.1 to about 5weight percent of a phosphine oxide photoinitiator.

[0066] In another embodiment, the curable composition comprises thereaction product of (meth)acrylic acid with a di-epoxide that isbisphenol-A diglycidyl ether, bisphenol-F diglycidyl ether, tetrabromobisphenol-A diglycidyl ether, tetrabromo bisphenol-F diglycidyl ether,1,3-bis-{4-[1-methyl-1-(4-oxiranylmethoxy-phenyl)-ethyl]-phenoxy}-propan-2-ol,1,3-bis-{2,6-dibromo-4-[1-(3,5-dibromo-4-oxiranylmethoxy-phenyl)-1-methyl-ethyl]-phenoxy}-propan-2-ol,or a combination comprising at least one of the forgoing di-epoxides;phenylthioethyl (meth)acrylate, phenoxyethyl (meth)acrylate, or acombination comprising at least one of the foregoing substituted orunsubstituted arylether (meth)acrylate monomer; pentabromobenzyl(meth)acrylate; and a phosphine oxide photoinitiator.

[0067] In yet another embodiment, a method of making the compositioncomprises blending a multifunctional (meth)acrylate, a substituted orunsubstituted arylether (meth)acrylate monomer, a brominated aromatic(meth)acrylate monomer, and a polymerization initiator.

[0068] Other embodiments include the reaction product obtained by curingany of the above curable compositions.

[0069] Still other embodiments include articles made from any of thecured compositions. Articles that may be fabricated from thecompositions include, for example, optical articles, such as lightmanagement films for use in back-light displays; projection displays;traffic signals; illuminated signs; optical lenses; Fresnel lenses;optical disks; diffuser films; holographic substrates; or as substratesin combination with conventional lenses, prisms or mirrors.

[0070] The invention is further illustrated by the followingnon-limiting examples.

EXAMPLES

[0071] The formulations for the following Examples were prepared fromthe components listed in Table 1. TABLE 1 Component Trade NameDescription Source RDX51027 RDX51027 Diacrylate of tetrabromo UCBChemicals bisphenol-A di-epoxide PTEA BX-PTEA Phenylthioethyl acrylateBimax Company PEA SR339 2-Phenoxyethyl acrylate Sartomer PBrBA FR1025MPentabromobenzyl Ameribrom acrylate Irgacure Irgacure 819 Bis(2,4,6-Ciba-Geigy trimethylbenzoyl)- phenylphosphine oxide Darocur Darocur2-Hydroxy-2-methyl-1- Ciba Specialty 4265 phenyl- Chemicals propan-1-oneand Bis(2,4,6- trimethylbenzoyl)- phenylphosphine oxide

[0072] Examples of cured flat films and cured microstructured filmscoated on a substrate were prepared according to the followingprocedures. As used in the Examples, coated films means a two-layeredfilm of the composition and film substrate. Coated cured flat filmshaving a 7 to 10 micrometer thick cured composition layer atop a0.005-inch (0.127 centimeter) thick polycarbonate film substrate wereprepared using a custom-made laminating unit and Fusion EPIC 6000UVcuring system. The laminating unit consists of two rubber rolls: abottom variable speed drive roll and a pneumatically driven top niproll. This system is used to press together laminate stacks that arepassed between the rolls. The laminate stacks contain a tool (also knownas a mold) with or without a desired geometry to replicate lying faceup, a curable composition coated on the tool, and a film substrate onthe top of the curable composition. The coated flat films were preparedby transferring approximately 0.5 mL of curable composition to a highlypolished, flat, chrome-plated 5 by 7-inch (12.7 by 17.8 centimeter)steel plate tool in a continuous line at the front, or leading edge ofthe plate. A piece of film substrate was then placed over the curablecomposition and the resulting stack sent through the laminating unit topress and distribute the curable composition uniformly between the tooland film substrate. With higher viscosity formulations, higher pressureand lower speeds were used and the tool was heated to obtain the desiredthickness. Photopolymerization of the curable composition within thestack was accomplished by passing the stack twice under a 600-wattV-bulb at a speed of 16 feet/minute (0.081 meters/second), using highpower and a focal length of 2.1 inches (5.3 centimeter), curing throughthe film substrate top layer. The coated cured flat film was then peeledoff of the flat tool and used for abrasion, % haze, % transmission,color, yellowness index, and adhesion measurements.

[0073] Coated cured microstructured films for measuring luminance weremade in the same manner as coated cured flat films by substituting thehighly polished flat steel plate for an electroformed tool with aprismatic geometry. The geometry of the prisms can be found in FIG. 6 ofthe copending U.S. application Ser. No. 10/065,981 entitled “BrightnessEnhancement Film With Improved View Angle” filed Dec. 6, 2002, which isincorporated by reference herein in its entirety.

[0074] Glass transition temperatures (Tg) of the cured compositions weremeasured by dynamic mechanical analysis (DMA) using a Rheometrics SolidsAnalyzer RSA II operating in tension with a frequency of 1.0 rad/s,strain of 0.01%, and temperature ramp of 2° C./minute. Cured free films(no film substrate) for DMA were prepared by placing approximately onegram of a curable composition into an aluminum pan having a 2 inch (5.08centimeter) diameter, spreading the curable composition across thebottom of the pan by tilting it, and photopolymerizing the compositionunder a nitrogen atmosphere. If the curable composition was viscous, thepan and curable composition were mildly heated to reduce the viscosityand enhance the flowability. Photopolymerization was accomplished usinga Fusion EPIC 6000 UV processor equipped with a 600 watt V-bulb. Thedistance of the lamp from the conveyor belt was 2.1 inches (5.3centimeter). The belt speed used was 16 feet/minute (0.081meters/second) and the sample was passed under the lamp three times.

[0075] The refractive index (RI) of the liquid curable compositions wasmeasured using a Bausch and Lomb Abbe-3L refractometer; the wavelengthassociated with the measurement was 589.3 nanometers.

[0076] The percent (%) haze and % transmission of light through thecoated cured flat films were determined according to ASTM D1003 using aBYK-Gardner Haze-guard Plus Hazemeter.

[0077] Oscillating Sand Abrasion Test (OST % haze) was performed on thecoated cured flat films using a modification to the procedure describedin ASTM F735. The major modification consisted of a change in the modeof sand oscillation from linear oscillation to circular oscillation. Theapparatus used for the abrasion process was a vortex shaker manufacturedby Glas-Col Company equipped with a metal tray to hold the sample andsand. The sand was silica sand from Fairmount Minerals of Wedron, Ill.(C.A.S. 14808-60-7). One thousand milliliters of sand and an oscillationtime of 10 minutes were used for the test. The change in haze after thesand abrasion test was used to represent abrasion resistance.

[0078] The brightness of the coated cured microstructured films wasdetermined using the Display Analysis system Microvision SS220.Microvision SS220, a computer based measurement system, uses agoniometric assembly and a mechanical positioner for the collection ofin-axis and off-axis data at various locations of the films. Thebrightness measurements are achieved by utilizing a diffraction gratingspectrometer with a collimation optical probe. The microstructured orlight management film is mounted on an LG-Phillips backlight module,which is composed of a bottom diffuser D177 and crossed light managementfilms. A 13 point test and hemi test are conducted to provide theuniformity of the brightness over 13 specific locations on the film andthe range of viewing angle at the center location of the film. Thebrightness is provided in units of candela per meter squared (cd/m²).

[0079] The adhesion was measured for the coated cured flat filmaccording to ASTM D3359.

[0080] The viscosity for each curable composition included in thefollowing examples was measured using a Brookfield LVDV-II Cone/PlateViscometer at 25° C., with a CPE40 or CPE51 spindle attachment, 0.5 mLliquid curable composition sample volume while maintaining a torquerange within 15% to 90% of the equipment maximum for the specific coneattachment. The viscosity measurements are provided in centipoise (cP).

[0081] The color of the coated cured flat films was determined bymeasuring L*, a*, and b* using a Gretag Macbeth Color-Eye 7000Acolorimeter using L*, a*, b* color space, the D65 illuminant, and a 10degree observer inclusive of a specular reflection.

[0082] The yellowness index (YI) of the coated cured flat films wasmeasured using a Gretag Macbeth Color-Eye 7000A colorimeter.

[0083] Table 2 provides glass transition temperature data for free filmsmade from PTEA and RDX⁵¹⁰²⁷ (Examples 1-4) and free films made fromPTEA, RDX51027, and PBrBA (Examples 5-8). The results illustrate thedramatic increase in Tg of the resulting cured compositions made fromformulations containing PBrBA. In the following tables, all of theamounts are shown in weight percent based on the total weight of thecomposition, with the actual amount of each component of the formulationenclosed in parenthesis (in grams). TABLE 2 Components in Weight percent(grams) Example RDX51027 PTEA PBrBA Irgacure Tg (° C.) 1 69.5 (7) 30 (3)— 0.5 (0.05) 90 2 59.5 (6) 40 (4) — 0.5 (0.05) 63 3 49.5 (5) 50 (5) —0.5 (0.05) 47 4 39.5 (4) 60 (6) — 0.5 (0.05) 28 5 69.5 (7) 21 (2.1)  9(0.9) 0.5 (0.05) 99 6 59.5 (6) 28 (2.8) 12 (1.2) 0.5 (0.05) 86 7 49.5(5) 35 (3.5) 15 (1.5) 0.5 (0.05) 71 8 39.5 (4) 42 (4.2) 18 (1.8) 0.5(0.05) 54

[0084] Table 3 provides glass transition data for free films made fromPEA and RDX51027 (Examples 9, 13, 17, and 21) and free films made fromPEA, RDX51027, and PBrBA (Examples 10-12, 14-16, 18-20, and 22-24). Theresults illustrate the dramatic increase in Tg of the resulting curedcompositions containing PBrBA. Again, the amounts are shown in weightpercent with the actual amount of each component of the formulationenclosed in parenthesis (in grams). TABLE 3 Components in Weight percent(grams) Tg Example RDX51027 PEA PBrBA Irgacure (° C.)  9 69.5 (7) 30 (3)— 0.5 (0.05) 93 10 69.5 (7) 27 (2.7)  3 (0.3) 0.5 (0.05) 101 11 69.5 (7)24 (2.4)  6 (0.6) 0.5 (0.05) 106 12 69.5 (7) 21 (2.1)  9 (0.9) 0.5(0.05) 112 13 59.5 (6) 40 (4) — 0.5 (0.05) 74 14 59.5 (6) 36 (3.6)  4(0.4) 0.5 (0.05) 79 15 59.5 (6) 32 (3.2)  8 (0.8) 0.5 (0.05) 91 16 59.5(6) 28 (2.8) 12 (1.2) 0.5 (0.05) 96 17 49.5 (5) 50 (5) — 0.5 (0.05) 5718 49.5 (5) 45 (4.5)  5 (0.5) 0.5 (0.05) 65 19 49.5 (5) 40 (4.0) 10(1.0) 0.5 (0.05) 70 20 49.5 (5) 35 (3.5) 15 (1.5) 0.5 (0.05) 78 21 39.5(4) 60 (6) — 0.5 (0.05) 45 22 39.5 (4) 54 (5.4)  6 (0.6) 0.5 (0.05) 4823 39.5 (4) 48 (4.8) 12 (1.2) 0.5 (0.05) 56 24 39.5 (4) 42 (4.2) 18(1.8) 0.5 (0.05) 66

[0085] Table 4 displays formulations for compositions of RDX51027, PTEA,and PBrBA. TABLE 4 Components in Weight percent (grams) Exam- PTEA: pleRDX51027 PTEA PBrBA PBrBA Irgacure 25 69.5 (10.46) 27 3 90:10 (4.48) 0.5(0.08) 26 59.5 (10.15) 36 4 90:10 (6.77) 0.5 (0.085) 27 49.5 (9.54) 45 590:10 (9.54) 0.5 (0.095) 28 39.5 (11.33) 54 6 90:10 (17.00) 0.5 (0.14)29 69.5 (10.96) 24 6 80:20 (4.70) 0.5 (0.078) 30 59.5 (9.58) 32 8 80:20(6.39) 0.5 (0.080) 31 49.5 (10.43) 40 10 80:20 (10.43) 0.5 (0.104) 3239.5 (9.13) 48 12 80:20 (13.70) 0.5 (0.114)

[0086] Table 5 displays data on free films and coated cured flat filmsproduced from curing films of the compositions in Table 4. The resultsillustrate that increasing PBrBA concentration in the compositionsincreases refractive index (RI) and Tg of the curable composition andcured free films, respectively. TABLE 5 Examples Properties 25 26 27 2829 30 31 32 RI Measured (liquid) 1.594 1.589 1.582 1.581 1.596 1.5931.588 1.585 % Haze 0.17 0.44 1.27 1.23 1.23 1.27 1.25 1.28 OST % Haze81.1 77.0 68.0 65.7 77.8 76.7 77.9 38.4 Adhesion 0B 5B 5B 5B 0B 0B 1B 5BViscosity (cP) NA 2,130 580 135 NA 3,570 873 250 Tg (° C.) 98 74 48 38101 80 30 52 L* 95.7 95.9 95.8 95.8 95.7 95.8 95.8 95.8 a* −0.1 0.0 0.00.0 −0.2 0.0 0.0 0.0 b* 0.5 0.3 0.3 0.3 0.8 0.4 0.3 0.3 YI 0.8 0.5 0.40.4 1.2 0.6 0.5 0.4

[0087] Table 6 displays formulations based on compositions derived fromRDX51027, PTEA, and PBrBA. TABLE 6 Components in Weight percent (grams)Example RDX51027 PTEA PBrBA Irgacure 33 29.5 (5.9) 56 (11.2) 14 (2.8)0.5 (0.1) 34 29.5 (5.9) 70 (14) — 0.5 (0.1) 35 49.5 (9.9) 50 (10.0) —0.5 (0.1) 36 49.5 (9.9) 45 (9.0)  5 (1.0) 0.5 (0.1) 37 49.5 (9.9) 40(8.0) 10 (2.0) 0.5 (0.1) 38 69.5 (13.9) 30 (6.0) — 0.5 (0.1) 39 69.5(13.9) 27 (5.4)  3 (0.6) 0.5 (0.1) 40 69.5 (13.9) 24 (4.8)  6 (1.2) 0.5(0.1)

[0088] Table 7 displays data on free films, coated cured flat films aswell as coated cured microstructured films produced from thecompositions in Table 6. Brightness of the samples in Table 7 weremeasured on the same day to offset day to day variations in brightnessreadings. The results of Examples 33 and 34 illustrate that the presenceof PBrBA in the compositions provides an unexpected increase inbrightness in the resulting microstructured films. Furthermore, theaddition of only small amounts of PBrBA to formulations containing about70 percent of the RDX compound resulted in free films havingsubstantially increased Tg (Examples 38-40). TABLE 7 Examples Properties33 34 35 36 37 38 39 40 RI Measured (liquid) 1.579 1.569 1.5777 1.58181.5861 1.5878 1.5910 1.5942 % Haze 0.59 0.55 0.61 0.65 0.67 0.64 0.600.64 Adhesion 5B 5B 5B 5B 5B 5B 5B 5B Viscosity (cP) 56 29 216 334 5335,743 10,629 20,481 Tg (° C.) 33 28 49 54 66 88 95 106 L* 95.8 95.9 95.995.9 95.8 95.9 95.9 95.9 a* 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 b* 0.4 0.30.4 0.4 0.4 0.3 0.3 0.4 YI 0.6 0.6 0.6 0.6 0.6 0.5 0.6 0.6 Transmission(%) 92.7 92.7 92.7 92.8 92.8 92.9 92.7 92.7 Brightness (cd/m²) 1491 1431— — — — — —

[0089] Table 8 provides the formulations for compositions comprisingRDX51027, PEA, and PBrBA. TABLE 8 Components in Weight percent (grams)Example RDX51027 PEA PBrBA Irgacure 41 29.5 (5.9)   56 (11.2)  14 (2.8)0.5 (0.1) 42 29.5 (5.9)   70 (14) — 0.5 (0.1) 43 49.5 (9.9)   50 (10.0)— 0.5 (0.1) 44 49.5 (9.9) 47.5 (9.5) 2.5 (0.5) 0.5 (0.1) 45 49.5 (9.9)42.5 (8.5) 7.5 (1.5) 0.5 (0.1) 46 49.5 (9.9)   40 (8.0)  10 (2.0) 0.5(0.1) 47 69.5 (13.9)   30 (6.0) — 0.5 (0.1) 48 69.5 (13.9)   27 (5.4)  3 (0.6) 0.5 (0.1) 49 69.5 (13.9)   24 (4.8)   6 (1.2) 0.5 (0.1)

[0090] Table 9 displays data on free films, coated cured flat films, andcoated cured microstructured films produced from curing the compositionsin Table 8. As with the PTEA formulations of Table 6 and 7, the resultsin Examples 41 and 42 illustrate that the presence of PBrBA in the PEAcontaining compositions provides an unexpected increase in brightness inthe resulting microstructured films. Also, the addition of minor amountsof PBrBA to the formulations containing about 70% of the RDX compoundresulted in cured free films having significantly increased Tg (Examples47-49). TABLE 9 Examples Properties 41 42 43 44 RI Measured (liquid)1.552 1.538 1.5530 1.5563 % Haze 0.59 0.47 0.63 0.66 Adhesion 5B 5B 5B5B Viscosity (cP) 96 49 362 451 Tg (° C.) 48 31 58 60 L* 96.0 96.1 96.096.0 a* 0.0 0.0 0.0 0.0 b* 0.3 0.3 0.3 0.3 YI 0.5 0.5 0.5 0.5Transmission (%) 92.9 93.2 93.1 93.1 Brightness (cd/m²) 1470 1387 — —Examples Properties 45 46 47 48 49 RI Measured (liquid) 1.5617 1.56501.5719 1.5764 1.5803 % Haze 0.65 0.62 .60 .60 .68 Adhesion 5B 5B 5B 5B5B Viscosity (cP) 743 1015 11,179 19,316 34,459 Tg (° C.) 67 69 97 104113.5 L* 96 96.0 96.0 95.9 95.9 a* 0.0 0.0 0.0 0.0 0.0 b* 0.3 0.3 0.30.3 0.3 YI 0.5 0.5 0.5 0.5 0.5 Transmission (%) 93.0 93.0 92.9 92.9 92.6Brightness (%) — — — — —

[0091] Comparing similar samples of PTEA, RDX51027 and PBrBA (Example33) with PEA, RDX51027 and PBrBA (Example 41) it is discovered that theformulation containing the PTEA has better RI than its PEA counterpart.Example 33 also provides a curable composition having a lower viscositythan Example 41, thereby providing better processability than a moreviscous composition. Finally, Example 33 provides a curedmicrostructured film having improved brightness when compared to its PEAcounterpart.

[0092] Table 10 provides the formulations of compositions comprising acombination of PTEA and PEA in addition to the RDX51027 and the PBrBA.TABLE 10 Components in Weight percent (grams) Example RDX51027 PEA PTEAPBrBA Irgacure 50 29.5 (5.9)   35 (7.0)   35 (7.0) — 0.50 (0.1) 51 29.5(5.9) 31.5 (6.3) 31.5 (6.3)  7 (1.4) 0.50 (0.1) 52 29.5 (5.9)   28 (5.6)  28 (5.6) 14 (2.8) 0.50 (0.1)

[0093] Table 11 provides the data of the cured free films and coatedcured flat films based on the formulations found in Table 10. As shownin Table 11, the addition of PBrBA increases Tg of cured free films andRI of the curable composition. TABLE 11 Examples Properties 50 51 52 RIMeasured (liquid) 1.5525 1.5590 1.5662 % Haze 0.56 0.53 0.63 Adhesion 5B5B 5B Viscosity (cP) 37 51 76 Tg (° C.) 25 31 37 L 96.0 95.9 95.9 a 0.00.0 0.0 b 0.3 0.3 0.3 YI 0.5 0.5 0.5 Transmission (%) 93.0 92.8 92.7

[0094] Since PBrBA is a powder and RDX51027 is a solid, the maximumamount of PBrBA that can be added to a blend of RDX51027 and substitutedor unsubstituted arylether (meth)acrylate monomer is dependent on thesolubility of PBrBA in the substituted or unsubstituted arylether(meth)acrylate monomer. The maximum solubility of PBrBA in PEA or PTEAwas determined as follows. Solutions of PBrBA in PTEA, PEA, or 50/50wt./wt. PTEA/PEA were prepared at different concentrations by heatingthe materials to promote solubility. The homogenous solutions were thenallowed to sit overnight at room temperature and the appearance ofcrystallization was observed visually. The data obtained is shown inTable 12. The results show that PTEA offers higher solubility of PBrBAthan PEA. TABLE 12 Wt. % PBrBA Reactive Diluent Crystallizationovernight 10 PEA No 20 PEA No 30 PEA Yes 10 PTEA No 20 PTEA No 30 PTEANo 10 50/50 PTEA/PEA No 20 50/50 PTEA/PEA No 30 50/50 PTEA/PEA Yes

[0095] Table 13 provides the formulations of compositions comprisingeither PEA or PTEA in addition to the RDX51027 without the presence ofPBrBA. Furthermore, two different photoinitiators were used in theformulations. All amounts are in weight percent. The following Examplesillustrate the unexpected increase in brightness of a formedmicrostructured film prepared from PTEA as compared to microstructuredfilm prepared from PEA. TABLE 13 Example (No. of Components in WeightPercent replicates) RDX51027 PEA PTEA Irgacure Darocur 53 (3) 59.7539.75 — 0.5 — 54 (5) 59.75 — 39.75 0.5 — 55 (3) 59.75 39.75 — — 0.5 56(3) 59.75 — 39.75 — 0.5

[0096] Table 14 provides brightness data measured on the same day formicrostructured films for two comparisons of PEA and PTEA formulations,Examples 53-56. Both absolute brightness and relative brightness ascompared to a daily standard are included with 95% confidence intervals;the number of replicated samples is included in parentheses with theExample number. TABLE 14 Optical Examples (No. of replicates)Performance 53 (3) 54 (5) 55 (3) 56 (3) Brightness (cd/m²) 1095.691125.30 1092.84 1117.20 95% CI   6.07   6.94   7.84   3.32 Brightness(daily 100.52% 102.08% 100.26% 102.11% standard) 95% CI  0.55%  0.62% 0.72%  0.30%

[0097] Both comparisons show that there is statistically significantincrease in brightness of the microstructure films when prepared from acomposition containing PTEA rather than PEA.

[0098] Examples 57 to 62 were prepared to explore the relative degree ofcure of compositions prepared from RDX51027, PTEA, and Irgacure 819cured under a variety of conditions. Coated flat films were prepared asdescribed above and according to the formulations described in Table 16.RX 02686 is an 80/20 (w/w) blend of RDX51027 and PTEA. The films ofcured material were 20-30 micrometers in thickness.

[0099] The relative degree of cure of cured, coated films was determinedby employing an Attenuated Total Reflectance Fourier Transform InfraredSpectroscopy (ATR-FTIR) analysis method. Attenuated total reflectance(ATR) spectra of both the uncured composition and the correspondingcured films were obtained. Specifically, the cured, coated films werecured using one of three different processing conditions as set out inTable 15 (dose in units of joules/cm²). ATR spectra of cured, coatedfilms were obtained by examining the film with a single-bounce ASIDiComp(R) accessory mounted in a Nicolet Magna(R) 750 FTIR. Theinstrument was configured with a potassium bromide (KBr) beamsplitterand an MCT-B detector. The film was placed over the diamond opticalelement with the coated side in contact with the diamond. Pressure wasapplied from the backside of the film to assure intimate contact. Themaximum pressure obtainable was set by lowering the adjustable plungeron the DiComp accessory to its lowest position. Spectra were obtained at2 wavenumber resolution by averaging 64 scans and performing the Fouriertransform. The spectra were used without additional processing. Spectraof the uncured liquid materials were obtained by placing a drop of theliquid composition on the ATR diamond optical element. TABLE 15Conditions Low dose Medium dose High dose Belt speed 48 feet/minute 48feet/minute 10 feet/minute Lamp height  8 inches  2 inches  2 inches UVAdose 0.176 0.289 1.631

[0100] The spectra were analyzed using the Nicolet OMNIC(R) softwarepackage. From the spectra, the area of two peaks between 1600 to 1645cm⁻¹ corresponding to vinyl peaks of the composition was obtained.Additionally, the area of a peak at 1537 cm⁻¹ was obtained correspondingto a non-vinyl reference peak that is present in both the uncuredmaterial and cured films. From the peak areas, the relative degree ofcure was calculated as follows: $\begin{matrix}{{Relative}\quad {degree}} \\{{of}\quad {cure}}\end{matrix} = {\left\lbrack \frac{\left( {\frac{{vinyl}\quad {liquid}}{1537\quad {cm}^{- 1}\quad {liquid}} - \frac{{vinyl}\quad {cured}}{1537\quad {cm}^{- 1}\quad {cured}}} \right)}{\frac{{vinyl}\quad {liquid}}{1537\quad {cm}^{- 1}\quad {liquid}}} \right\rbrack \times 100}$

[0101] The ratio of the area of the vinyl peaks to the area of thereference peak for the uncured composition corresponds to “Vinylliquid/1537 cm⁻¹ liquid” and is provided in Table 16 as “Vinyl/1537liquid”. The ratio of the area of the vinyl peaks to the area of thereference peak for the cured film corresponds to “Vinyl cured/1537 cm⁻¹cured” and is provided in Table 16 as “Vinyl/1537 high dose”,“Vinyl/1537 med. dose”, and “Vinyl/1537 low dose” for cured films athigh, medium, and low dose conditions of Table 15, respectively. Fromthe ratios, the degree of cure was calculated and is provided in Table16 along with additional property data of the resulting cured films.TABLE 16 Examples 57 58 59 60 61 62 Components RX 02686 (grams) 18.6218.25 20.96 20.59 23.31 22.94 PTEA (grams) 6.25 6.25 3.91 3.91 1.56 1.56Irgacure 819 (grams) 0.13 0.50 0.13 0.50 0.13 0.50 Properties Viscosity@ 25° C. (cP) 992 1,006 4,048 4,096 22,714 23,927 RI liquid 1.58781.5879 1.5911 1.5916 1.5955 1.5957 Vinyl/1537 liquid 1.9044 1.85031.2595 1.1246 1.116 Vinyl/1537 high dose 0.1865 0.10812 0.1764 0.13860.2166 0.1521 Vinyl/1537 med. dose 0.1903 0.2310 0.2135 0.1622 0.30640.2429 Vinyl/1537 low dose 0.26784 0.22052 0.2310 0.1864 0.2959 0.2691Degree of cure high dose 90.207 94.157 90.875 94.509 85.994 88.996Degree of cure med. dose 90.007 87.516 81.726 89.682 83.049 87.122Degree of cure low dose 85.936 88.082 80.002 88.457 81.659 85.200Adhesion low dose 2B 5B 5B 5B 5B 5B Adhesion med. dose 5B 5B 5B 5B 5B 5BAdhesion high dose 5B 5B 5B 5B 5B 5B Haze low dose 0.73 0.68 0.70 1.080.70 0.73 Haze med. dose 0.69 0.71 0.67 0.72 0.71 0.78 Haze high dose0.76 0.72 0.73 0.70 0.98 0.82 Transmission (%) low dose 92.7 92.7 92.792.6 92.7 92.6 Transmission (%) med. dose 92.6 92.7 92.6 92.7 92.7 92.6Transmission (%) high dose 92.7 92.7 92.7 92.7 92.5 92.5 Abrasion lowdose 85.45 85.98 84.26 84.16 85.88 85.19 Abrasion medium dose 84.6384.40 84.26 83.67 86.01 84.19 Abrasion high dose 82.21 81.48 82.09 81.4981.3 81.56 L* low dose 95.8 95.8 95.8 95.8 95.8 95.8 a* low dose −0.1−0.3 0.0 −0.2 −0.1 −0.5 b* low dose 0.4 0.8 0.4 0.8 0.5 1.2 YI low dose0.6 1.1 0.6 1.0 0.6 1.3 L* med. dose 95.8 95.8 95.8 95.8 95.8 95.8 a*med. dose 0.0 −0.2 0.0 −0.2 −0.1 −0.3 b* med. dose 0.40 0.7 0.4 0.6 0.41.0 YI med. dose 0.6 1.0 0.6 0.9 0.6 1.3 L* high dose 95.8 95.8 95.895.8 95.8 95.8 a* high dose 0 −0.1 0.0 −0.1 0.0 −0.1 b* high dose 0.40.5 0.4 0.5 0.4 0.6 YI high dose 0.6 0.7 0.6 0.7 0.6 0.9

[0102] As illustrated by the results in Table 16, the RDX and PTEAcompositions provide a cured material having excellent properties andexcellent degree of cure, often above 80 percent even when processed ata low dose of UVA radiation. Such a high degree of cure under theprocessing conditions outlined in Table 15 indicate that thecompositions provided herein are well suited for the high speedproduction of cured, coated films, especially in continuous processes.The high degree of cure allows for increased productivity in themanufacturing process and the reduction of costs.

[0103] While the invention has been described with reference to apreferred embodiment, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing fromessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A curable composition, comprising: a multifunctional (meth)acrylaterepresented by the formula:

wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2; and R²is represented by the formula:

wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y is divalentC₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; a substituted orunsubstituted arylether (meth)acrylate monomer according to the formula:

wherein R³ is hydrogen or methyl; X² is O or S; R⁴ is substituted orunsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar is substituted orunsubstituted C₆-C₁₂ aryl, including phenyl; wherein the substitution onthe R⁴ and Ar independently include fluorine, chlorine, bromine, iodine,C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ ketone, C₁-C₆ester, N,N-(C₁-C₃) alkyl substituted amide, or a combination comprisingat least one of the forgoing substituents; and a polymerizationinitiator.
 2. The composition of claim 1, comprising: about 25 to about75 weight percent multifunctional (meth)acrylate; about 15 to about 70weight percent substituted or unsubstituted arylether (meth)acrylatemonomer; and about 0.1 to about 10 weight percent polymerizationinitiator based on the total weight of the composition.
 3. Thecomposition of claim 1, comprising: about 50 to about 70 weight percentmultifunctional (meth)acrylate; about 30 to about 50 weight percentsubstituted or unsubstituted arylether (meth)acrylate monomer; and about0.1 to about 10 weight percent polymerization initiator based on thetotal weight of the composition.
 4. The composition of claim 1, whereinthe multifunctional (meth)acrylate is the reaction product of(meth)acrylic acid with a di-epoxide comprising bisphenol-A diglycidylether; bisphenol-F diglycidyl ether; tetrabromo bisphenol-A diglycidylether; tetrabromo bisphenol-F diglycidyl ether;1,3-bis-{4-[1-methyl-1-(4-oxiranylmethoxy-phenyl)-ethyl]-phenoxy}-propan-2-ol;1,3-bis-{2,6-dibromo-4-[1-(3,5-dibromo-4-oxiranylmethoxy-phenyl)-1-methyl-ethyl]-phenoxy}-propan-2-ol;or a combination comprising at least one of the foregoing di-epoxides;and wherein the substituted or unsubstituted arylether (meth)acrylatemonomer according to the formula:

wherein R³ is hydrogen or methyl; X² is O or S; R⁴ is divalent C₁-C₆alkyl; and Ar is phenyl.
 5. The composition of claim 1, wherein themultifunctional (meth)acrylate is

wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y is divalentC₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b is 1; t is 2;and d is 1; or wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or—S(O)₂—; Y is divalent C₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆alkyl; b is 1; t is 2; and d is 2; or a combination thereof.
 6. Thecomposition of claim 1, wherein the substituted or unsubstitutedarylether (meth)acrylate monomer is phenylthioethyl acrylate orphenylthioethyl methacrylate.
 7. The composition of claim 1, furthercomprising a brominated aromatic (meth)acrylate monomer according to theformula:

wherein R⁵ is hydrogen or methyl; X⁴ is O or S; X⁵ is O or S; m is 1, 2,or 3; p is 0 or 1; and q is 1, 2, 3, 4, or
 5. 8. The composition ofclaim 7, wherein the brominated aromatic (meth)acrylate monomer istribromobenzyl (meth)acrylate, tribromophenyl (meth)acrylate,pentabromobenzyl (meth)acrylate, pentabromophenyl (meth)acrylate or acombination comprising at least one of the foregoing brominated aromatic(meth)acrylate monomers.
 9. The composition of claim 7, wherein thebrominated aromatic (meth)acrylate monomer is present at about 1 toabout 20 weight percent based on the total weight of the composition.10. The composition of claim 1, wherein the polymerization initiator isa phosphine oxide photoinitiator.
 11. The composition of claim 1,further comprising a flame retardant, antioxidant, thermal stabilizer,ultraviolet stabilizer, dye, colorant, anti-static agent, surfactant, ora combination comprising at least one of the foregoing additives. 12.The composition of claim 1, wherein the refractive index of thecomposition is greater than or equal to about 1.58.
 13. An optical filmcomprising a reaction product of the composition of claim
 1. 14. Theoptical film of claim 13, comprising a degree of cure of greater thanabout 80 percent after exposure to a WVA dose of about 0.289 joules/cm².15. An optical film for backlit displays comprising a reaction productof the composition of claim
 1. 16. A curable composition, consistingessentially of: a multifunctional (meth)acrylate represented by theformula:

wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2; and R²is represented by the formula:

wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y is divalentC₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; a substituted orunsubstituted arylether (meth)acrylate monomer according to the formula:

wherein R³ is hydrogen or methyl; X² is O or S; R⁴ is substituted orunsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar is substituted orunsubstituted C₆-C₁₂ aryl, including phenyl; wherein the substitution onthe R⁴ and Ar independently include fluorine, chlorine, bromine, iodine,C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ ketone, C₁-C₆ester, N,N-(C₁-C₃) alkyl substituted amide, or a combination comprisingat least one of the forgoing substituents; and a polymerizationinitiator.
 17. The curable composition of claim 16, consisting of amultifunctional (meth)acrylate represented by the formula:

wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2; and R²is represented by the formula:

wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y is divalentC₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; a substituted orunsubstituted arylether (meth)acrylate monomer according to the formula:

wherein R³ is hydrogen or methyl; X² is O or S; R⁴ is substituted orunsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar is substituted orunsubstituted C₆-C₁₂ aryl, including phenyl; wherein the substitution onthe R⁴ and Ar independently include fluorine, chlorine, bromine, iodine,C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ ketone, C₁-C₆ester, N,N-(C₁-C₃) alkyl substituted amide, or a combination comprisingat least one of the forgoing substituents; and a polymerizationinitiator.
 18. A curable composition, comprising: a multifunctional(meth)acrylate represented by the formula:

wherein R¹ is hydrogen or methyl; X¹ is O or S; n is at least 2; and R²is represented by the formula:

wherein Q is —C(CH₃)₂—, —CH₂—, —C(O)—, —S(O)—, or —S(O)₂—; Y is divalentC₁-C₆ alkyl or hydroxy substituted divalent C₁-C₆ alkyl; b isindependently at each occurrence 1 to 10; t is independently at eachoccurrence 0, 1, 2, 3, or 4; and d is 1 to 3; a substituted orunsubstituted arylether (meth)acrylate monomer represented by theformula:

wherein R³ is hydrogen or methyl; X² is O or S; X³ is O or S; R⁴ issubstituted or unsubstituted divalent C₁-C₆ alkyl or alkenyl; Ar issubstituted or unsubstituted C₆-C₁₂ aryl, including phenyl; wherein thesubstitution on the R⁴ and Ar independently include fluorine, chlorine,bromine, iodine, C₁-C₆ alkyl, C₁-C₃ perhalogenated alkyl, hydroxy, C₁-C₆ketone, C₁-C₆ ester, N,N-(C₁-C₃) alkyl substituted amide, or acombination comprising at least one of the forgoing substituents; abrominated aromatic (meth)acrylate monomer represented by the formula:

wherein R⁵ is hydrogen or methyl; X⁴ is O or S; X⁵ is O or S; m is 1, 2,or 3; p is 0 or 1; and q is 4 or 5; and a polymerization initiator. 19.The composition of claim 18, wherein the multifunctional (meth)acrylateis the reaction product of (meth)acrylic acid with a di-epoxidecomprising bisphenol-A diglycidyl ether; bisphenol-F diglycidyl ether;tetrabromo bisphenol-A diglycidyl ether; tetrabromo bisphenol-Fdiglycidyl ether;1,3-bis-{4-[1-methyl-1-(4-oxiranylmethoxy-phenyl)-ethyl]-phenoxy}-propan-2-ol;1,3-bis-{2,6-dibromo-4-[1-(3,5-dibromo-4-oxiranylmethoxy-phenyl)-1-methyl-ethyl]-phenoxy}-propan-2-ol;or a combination comprising at least one of the foregoing di-epoxides.20. The composition of claim 18, wherein the substituted orunsubstituted arylether (meth)acrylate monomer is phenoxyethyl(meth)acrylate, phenylthioethyl (meth)acrylate, or a combinationcomprising at least one of the foregoing substituted or unsubstitutedarylether (meth)acrylate monomers.
 21. The composition of claim 18,wherein the brominated aromatic (meth)acrylate monomer ispentabromobenzyl (meth)acrylate, pentabromophenyl (meth)acrylate, or acombination comprising at least one of the foregoing brominated aromatic(meth)acrylate monomers.
 22. The composition of claim 18, comprisingabout 25 to about 75 weight percent of the multifuictional(meth)acrylate; about 15 to about 70 weight percent of the substitutedor unsubstituted arylether (meth)acrylate monomer; about 1 to about 20weight percent of the brominated aromatic (meth)acrylate monomer; andabout 0.1 to about 5 weight percent of a phosphine oxide photoinitiatorbased on the total weight of the composition.
 23. An optical filmcomprising a reaction product of the composition of claim
 18. 24. Amethod of making the composition of claim 1, comprising: blending themultifunctional (meth)acrylate, the substituted or unsubstitutedarylether (meth)acrylate monomer, and the polymerization initiator.